Self-assembled flower-like spherical Bi2WO6/BiOBr S-scheme heterojunction: Improved charge transfer and excellent photocatalytic activity

The suppression of expeditious complexation of photoexcited carriers and the enhancement of light harvesting are two extraordinarily momentous elements for boosting the catalytic activity of synthesized semiconductor photocatalyst. Herein, a sequence of visible-light-induced self-assembled flower-like spherical Bi ₂WO ₆/BiOBr S-scheme heterojunctions were successfully fabricated by two-step solvothermal process. The fabricated Bi ₂WO ₆/BiOBr hybrids possessed the splendid capacity to catalyze the degradation of bisphenol A (BPA) in water without the addition of surfactant compared to monocomponent photocatalyst. The optimized Bi ₂WO ₆/BiOBr (FBBH-16) possessed the most prominent photocatalytic activity, acquiring a conspicuous degradation efficiency of 91.97 % ± 1.51 % for BPA after 60 min illumination. The rate constant k (0.04078 ± 0.0009985 min ⁻¹) of FBBH-16, which was approximately 4.0 and 3.5 times that of bare Bi ₂WO ₆ and BiOBr, respectively. Such strengthening mechanism was chiefly ascribed to the establishment of S-scheme heterojunction, which efficaciously impeded the complexation of photoexcited charge pairs and noteworthily heightened the light harvesting. Furthermore, the forceful interfacial interactions between Bi ₂WO ₆ and BiOBr afforded much more active sites for BPA removal. The quenching experiments confirmed that ·OH and ·O ²⁻ are the principal active species for BPA degradation over Bi ₂WO ₆/BiOBr hybrids. Ultimately, two possible photodegradation pathways of BPA over Bi ₂WO ₆/BiOBr heterojunctions are also come up with on the grounds of the identification of intermediate products. This work furnishes fresh insights into the fabrication of highly efficacious and stable bismuth-based S-scheme heterojunctions for treating the actual wastewater by integrating nanostructure and microscopic morphology.